[PATCH] D106613: Bad SLPVectorization shufflevector replacement, resulting in write to wrong memory location

[Jameson Nash via Phabricator via llvm-commits]

vtjnash added a comment.

The full reproducer is in the commit message on phabricator for this review, though I don't know how to link to the text of a commit specifically. Here's the text of that:

With `opt -mcpu=haswell -slp-vectorizer`, we see that it might currently produce:

  %10 = getelementptr {}**, <2 x {}***> %9, <2 x i32> <i32 10, i32 4>
  %11 = bitcast <2 x {}***> %10 to <2 x i64*>
  ...
  %27 = extractelement <2 x i64*> %11, i32 0
  %28 = bitcast i64* %27 to <2 x i64>*
  store <2 x i64> %22, <2 x i64>* %28, align 4, !tbaa !2

Which is an out-of-bounds store (the extractelement got offset 10
instead of offset 4 as intended). With the fix, we correctly generate
extractelement for i32 1 and generate correct code.

  ; ModuleID = 'rand3.ll'
  source_filename = "rand"
  target datalayout = "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-f64:32:64-f80:32-n8:16:32-S128-ni:10:11:12:13"
  target triple = "i686-unknown-linux-gnu"
  
  @llvm.compiler.used = appending global [3 x i8*] [i8* bitcast (void ({} addrspace(10)*)* @jl_gc_queue_root to i8*), i8* bitcast ({} addrspace(10)* (i8*, i32, i32)* @jl_gc_pool_alloc to i8*), i8* bitcast ({} addrspace(10)* (i8*, i32)* @jl_gc_big_alloc to i8*)], section "llvm.metadata"
  
  ; Function Attrs: sspstrong
  define void @julia_rand_5(i64* noalias nocapture sret(i64) %0) #0 {
  top:
  %1 = call {}*** @julia.get_pgcstack()
  %2 = getelementptr {}**, {}*** %1, i32 4
  %3 = bitcast {}*** %2 to i64*
  %4 = load i64, i64* %3, align 4, !tbaa !2
  %5 = getelementptr {}**, {}*** %1, i32 6
  %6 = bitcast {}*** %5 to i64*
  %7 = load i64, i64* %6, align 4, !tbaa !2
  %8 = getelementptr {}**, {}*** %1, i32 8
  %9 = bitcast {}*** %8 to i64*
  %10 = load i64, i64* %9, align 4, !tbaa !2
  %11 = getelementptr {}**, {}*** %1, i32 10
  %12 = bitcast {}*** %11 to i64*
  %13 = load i64, i64* %12, align 4, !tbaa !2
  %14 = add i64 %13, %4
  %15 = call i64 @llvm.fshl.i64(i64 %14, i64 %14, i64 23)
  %16 = shl i64 %7, 17
  %17 = xor i64 %10, %4
  %18 = xor i64 %13, %7
  %19 = xor i64 %17, %7
  %20 = xor i64 %18, %4
  %21 = xor i64 %17, %16
  %22 = call i64 @llvm.fshl.i64(i64 %18, i64 %18, i64 45)
  store i64 %20, i64* %3, align 4, !tbaa !2
  store i64 %19, i64* %6, align 4, !tbaa !2
  store i64 %21, i64* %9, align 4, !tbaa !2
  store i64 %22, i64* %12, align 4, !tbaa !2
  store i64 %15, i64* %0, align 4
  ret void
  }
  
  define nonnull {} addrspace(10)* @jfptr_rand_6({} addrspace(10)* %0, {} addrspace(10)** %1, i32 %2) #1 {
  top:
  %3 = call {}*** @julia.get_pgcstack()
  %4 = alloca i64, align 8
  call void @julia_rand_5(i64* noalias nocapture nonnull sret(i64) %4) #5
  %5 = load i64, i64* %4, align 8, !tbaa !7
  %6 = call nonnull {} addrspace(10)* @jl_box_uint64(i64 zeroext %5)
  ret {} addrspace(10)* %6
  }
  
  declare {}*** @julia.get_pgcstack()
  
  declare nonnull {} addrspace(10)* @jl_box_uint64(i64 zeroext)
  
  ; Function Attrs: inaccessiblemem_or_argmemonly
  declare void @jl_gc_queue_root({} addrspace(10)*) #2
  
  ; Function Attrs: allocsize(1)
  declare noalias nonnull {} addrspace(10)* @jl_gc_pool_alloc(i8*, i32, i32) #3
  
  ; Function Attrs: allocsize(1)
  declare noalias nonnull {} addrspace(10)* @jl_gc_big_alloc(i8*, i32) #3
  
  ; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
  declare i64 @llvm.fshl.i64(i64, i64, i64) #4
  
  attributes #0 = { sspstrong "probe-stack"="inline-asm" }
  attributes #1 = { "probe-stack"="inline-asm" "thunk" }
  attributes #2 = { inaccessiblemem_or_argmemonly }
  attributes #3 = { allocsize(1) }
  attributes #4 = { nofree nosync nounwind readnone speculatable willreturn }
  attributes #5 = { "probe-stack"="inline-asm" }
  
  !llvm.module.flags = !{!0, !1}
  
  !0 = !{i32 2, !"Dwarf Version", i32 4}
  !1 = !{i32 2, !"Debug Info Version", i32 3}
  !2 = !{!3, !3, i64 0}
  !3 = !{!"jtbaa_value", !4, i64 0}
  !4 = !{!"jtbaa_data", !5, i64 0}
  !5 = !{!"jtbaa", !6, i64 0}
  !6 = !{!"jtbaa"}
  !7 = !{!8, !8, i64 0}
  !8 = !{!"jtbaa_stack", !5, i64 0}


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106613/new/

https://reviews.llvm.org/D106613